That permanence is a bit of a myth. Bit rot is as real as physical one. At least four cloud storages (Bitcasa, hubiC, Ubuntu One, Cyphertite) I’ve used in the past are gone.

I want to emphasize "unknowingly" part. Once data is uploaded to an entity, there's no guarantee they'll manage is properly.

User agreements change constantly, engineers make mistake, firms get liquidated and data might get sold, and most importantly, as a former employee of social media firms, what the firms say about the user privacy publicly is very different inside.

But it has potential to be permanent through the means of other people storing copies of it. If you send a photo via WhatsApp to someone, for example, that photo is by default saved automatically to their phone, and potentially synced to their Google Photos.